c.1600, "to clear out the chest or lungs," a literal use of Latin expectoratus, past participle of expectorare, which in classical use was figurative, "scorn, expel from the mind," literally "drive from the breast, make a clean breast," from ex- "out" (see ex-) + pectus (genitive pectoris) "breast" (see pectoral (adj.)). Its use as a euphemism for "spit" is recorded by 1827. The classical Latin figurative sense appears in English 17c. but is now obsolete. Related: Expectorated; expectorating.